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Re: [PATCH] gas: allow labeling of CFI instructions
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Jan Beulich <JBeulich at suse dot com>
- Cc: Binutils <binutils at sourceware dot org>
- Date: Fri, 19 Dec 2014 06:32:17 -0800
- Subject: Re: [PATCH] gas: allow labeling of CFI instructions
- Authentication-results: sourceware.org; auth=none
- References: <549443A90200007800051089 at mail dot emea dot novell dot com>
On Fri, Dec 19, 2014 at 6:26 AM, Jan Beulich <JBeulich@suse.com> wrote:
> When runtime patching code (like e.g. done by the Linux kernel) there
> may be cases where the set of stack frame alterations differs between
> unpatched and patched code. Consequently the corresponding unwind data
> needs patching too. Locating the right places within an FDE, however,
> is rather cumbersome without a way to insert labels in the resulting
> section. Hence this patch introduces a new directive, .cfi_label. Note
> that with the way CFI data gets emitted currently (at the end of the
> assembly process) this can't support local FB- and dollar-labels.
> 2014-12-19 Jan Beulich <email@example.com>
> * gas/dw2gencfi.c (cfi_add_label, dot_cfi_label): New.
> (cfi_pseudo_table): Add "cfi_label".
> (output_cfi_insn): Handle CFI_label.
> (select_cie_for_fde): Als terminate CIE when encountering
> * dw2gencfi.h (cfi_add_label): Declare.
> (struct cfi_insn_data): New member "sym_name".
> (CFI_label): New.
> * read.c (read_symbol_name): Drop "static".
> * read.h (read_symbol_name): Declare.